Enigmas of the Oral Mycobiome: A Narrative Review of the Delicate Dance Between Commensal and Pathogenic Fungi

Abstract

Background: The oral cavity harbors diverse microbial communities essential for oral and systemic health. Dysbiosis, or disruption of this balance, contributes to disease. The objective of this review was to elucidate the complexity and dualistic nature of the oral mycobiome, emphasizing the interplay between commensal and pathogenic fungi.

Methods: A comprehensive review of current literature was conducted, focusing on the oral mycobiome—particularly the interplay between commensal and pathogenic fungi. Studies were selected based on relevance and quality, with key findings synthesized to provide a focused overview.

Results: Recent technological advances have revealed the oral microbiome’s complexity, extending beyond bacteria to include fungi and viruses. Candida species, especially C. albicans, dominate the healthy oral mycobiome, but their shift to pathogenicity is influenced by bacterial interactions, immunity, and host factors. Non-Candida fungi, such as Malassezia and Cladosporium, are consistently present in health, indicating broader ecological roles. Cross-kingdom interactions between fungi and bacteria foster biofilm formation, increasing resistance to therapy and contributing to oral diseases like caries and periodontitis. Fungal dysbiosis is associated with systemic conditions, including diabetes and HIV, with oral mycobiome shifts serving as both biomarkers and modulators of disease. Next-generation sequencing has highlighted inter-individual variability, shaped by genetics, environment, and diet. The oral mycobiome also modulates immune responses, influencing susceptibility to infection.

Conclusion This review synthesizes current knowledge on the oral mycobiome, emphasizing the specific roles and interactions of commensal and pathogenic fungi, factors shaping their balance, and their emerging clinical significance

Keywords: Oral Mycobiome. Commensal, Pathogen, Fungi